Tunneling machine with inclined cutting wheel



' Dec. 30, 1969 J. R. TAB OR 3,486,794 TUNNELING MACHINE WITH INCL INED CUTTING WHEEL Filed April 24, 1967 3 Sheets-Sheet 1 INVENTOZ JoH/v Z. 7250a 8v MAZQA/M ATTOZNEY5 TUNNELING MACHINE WITH INCLINED CUTTING WHEEL Filed April 24, 1967 J. R. TABOR Dec. 30, 1969 3 Sheets-Sheet 2 VE NTOQ Jar-1M B V ATTORNEY;

TUNNELING MACHINE WITH INCLINED CUTTING WHEEL Filed April 24, 1967 J. R. TABOR Dec. 30, 1969 3 Sheets-Sheet 5 INVENTOZ JOHN 2. 774502.

avAMfiMJ6m ATTORNEY$ United States Patent 3,486,794 TUNNELING MACHINE WITH INCLINED CUTTING WHEEL John R. Tabor, 3400 Spruce St., Racine, Wis. 53403 Filed Apr. 24, 1967, Ser. No. 632,979 Int. Cl. E2111 23/04; E02f 3/24 US. Cl. 29933 9 Claims ABSTRACT OF THE DISCLOSURE This disclosure relates to a tunneling machine comprising a shield, a rotary cutting wheel, and a rotary support means for the wheel on which the plane in which the wheel rotates is inclined toward the angle of repose of the soil.

CROSS REFERENCE TO RELATED APPLICATION Cross reference is made to my copending application Ser. No. 474,351, filed July 23, 1965, now U.S. Patent 3,382,002 granted May 7, 1968, which shows a rotary cutter wheel tunneling machine in which the cutting wheel is disposed in a vertical plane. In accordance with the present invention, such a rotary cutter wheel is inclined forwardly toward the angle of repose of the soil.

SUMMARY OF THE INVENTION By inclining the cutting wheel toward the angle of repose of the spoil, the holding or breasting force necessary to resist back pressure and the thrusting force needed to advance the wheel forwardly in the direction of tunneling is reduced. The torque requirements for turning the wheel are also reduced. The exact angle to which the wheel should be inclined is not readily ascertainable as the angle of repose of the soil will vary in accordance with the nature of the ground through which the tunnel is formed. Various earth formations have soil components which will assume different angles of repose. Mechanical considerations also enter into the determination of the desirable wheel inclination. Accordingly, the angle of wheel inclination may vary from one machine to another. Where a machine is to be used in different soil strata, the angle is calculated to accommodate for typical soil conditions.

Various features, advantages and objects of the invention include:

(1) Reduction of the soil or face load encountered at the wheel cutting face.

(2) Reduction in the complexity and cost of the supporting structure for the Wheel, because of the reduced load aforesaid.

(3) Stabilization of the working face to apply and maintain a more positive breasting force with less effort.

(4) Reduction of strain on the primary lining of the tunnel by reason of the reduction in face load.

(5) The reduction of the face load allows more freedom of navigation because face load forces are .more balanced.

(6) Spoil impact on the take-out conveyor is reduced by reason of the inclined wheel. Spoil does not fall 'directly on the conveyor, it is buffeted by the incline.

DESCRIPTION THE DRAWINGS FIG. 1 is an axial cross section taken through the head of a tunneling shield having a cutting wheel inclined in accordance with the present invention.

FIG. 2 is an enlarged fragmentary cross section taken along the line 22 of FIG. 1.

FIG. 3 is a cross section taken along the line 3-3 of FIG. 1.

3,486,794 Patented Dec. 30, 1969 FIGS. 4, 5 and 6 are diagrammatic views illustrating theoretical considerations relating to the angle of inclination of the cutting wheel.

FIGS. 7, 8 and 9 are diagrammatic views illustrating other theoretical considerations relating to said angle.

DESCRIPTION OF THE PREFERRED EMBODIMENT Although the disclosure hereof is detailed and exact to enable those skilled in the art to practice the invention, the physical embodiments herein disclosed merely exemplify the invention which may be embodied in other specific structure. The scope of the invention is defined in the claims appended hereto.

The tunneling machine may have substantially the same basic structure as shown in my copending application aforesaid, except that the cutting wheel 10 rotates on a plane which is inclined with respect to the vertical, as is illustrated in FIG. 1 hereof. The cutting wheel 10 is mounted within a shield 11 which has an inclined bulkhead 12 having a central opening 19 about which a group of hydraulic motors 13 are mounted. Bulkhead 12 is provided with support means for the wheel, including an annular wheel support race 14 which supports on ball bearings 16 a complementary annular wheel race 15 attached to the wheel 10. Bearing 14, 15, 16 is both an axial and a radial thrust bearing.

The respective hydraulic motors 13 have output shafts 17 with toothed drive wheels 18 which engage cog rollers 21 mounted on roller shafts 22 on the wheel race 15. The bearing 14, 15, 16 supports the wheel in its inclined position, and motors 13 are controlled to turn the wheel 10 in either direction of rotation.

Details of the wheel 10 are not illustrated herein, as these are shown in the copending application aforesaid, the disclosure of which is incorporated herein by reference. Wheel 10 confronts the major portion of the tunnel face.

As in the application aforesaid, the shield is thrust forwardly by means of the series of hydraulic jacks 23 about the periphery of the shield. Spoil cut from the face of the tunnel is discharged rearwardly by the conveyor 24 which may have a moving belt 25 or the like. The foremost end of the belt 25 is desirably within a hopper 26 to collect the spoil cut from the tunnel face by the wheel 10.

FIGS. 4, 5 and 6 diagrammatically illustrate theorotical considerations underlying the advantage of a forwardly inclined cutting wheel over one in which the face of the wheel is vertical. The shield is indicated at 11. The face of the wheel is indicated at 10. The curved line 30 represents the stress or force (both axial and torque) imposed upon the wheel by the soil through which the tunnel is made. Arrow 31 representsthe holding force which the wheel must exert to overcome the stresses exerted upon it by the soil, and bythe weight of the soil which is represented by the arrow 32.

. The angle of repose of the soil is indicated by the axis line Y. This line will be at an angle A to'the horizontal. For any particular soil, angle A and the slope of the axis lineY will be constant. For different soils, angle A and the slope of axis line Y will vary somewhat. Axis line Y also represents the line of friction of the soil. The force indicated by arrow 33 represents the tendency of the soil to slide by gravity along the line Y. This force is opposed by the force of friction, indicated by the arrow 34. When the soil is at its angle of repose the forces indicated by arrows 33, 34 exactly balance.

The axis line X is a line indicating the direction of force of said which is not held in balance by internal friction. This force is termed extra burden and is present when the wheel 10 is vertical, as shown in FIG. 4, or

at only a slight angle to the vertical, as shown in FIG. 5. The angle which axis line X makes with the horizontal is denominated angle B. Holding force 31 must equal the extra burden to hold or breast the force along line X. Force 31 must exceed the extra burden to thrust the wheel and shield forwardly through the soil.

In FIG. 5, the plane in which the cutting wheel 10 1'0- tates is shown at a slight inclination to the vertical, indicated by the angle a. Assuming the soil to be the same as in FIG. 4, the frictional resistance axis line Y remains the same, and angle A remains the same. However, the extra burden axis line X is at a reduced inclination (angle B is smaller) and is closer to coincidence with frictional axis line Y. This is because the curve 30 has a different shape in FIG. 5 than in FIG. 4, and axis line X has a correspondingly different inclination. In effect, more of the extra burden is supported by internal friction as the wheel is tilted toward the angle of respose of the soil and less unsupported force is imposed on the wheel. This condition is represented by a change in shape of curve 30 and a lessening of its encompassed area. Accordingly, holding or thrusting force 31 can be decreased.

In FIG. 6 the wheel has been tilted far enough forwardly to change the shape of stress curve 30 so that force axis line X coincides with frictional axis line Y. Angles A and B are now the same. The angle of inclination of the wheel is now indicated by angle b. Accordingly, there is no extra burden exerted along axis line X. All of the force exerted along axis line X is balanced by internal friction. The only unbalanced force is the weight of the soil indicated by arrow 32. Accordingly, in this theoretical analysis, the holding force 31 merely has to overcome the weight of the soil, inasmuch as the extra burden is completely sustained by the friction force 34.

Further inclination of the whel 10 beyond the angle b is regarded as undesirable. Beyond this inclination, the inclined wheel 10 would be subject to overturning forces.

From the foregoing it is clear that the holding or thrusting force 31 can be reduced for any forward incline of wheel 10, and that the greatest reduction is achieved when the extra burden axis line X is at the angle of respose of the soil.

Because of the fact that angles of repose of various soils differ from one location to another, in actual practice the wheel 10 is incined only enough to produce substantial reduction in the required thrusting and holding force. It has been determined that the angle of wheel inclination can be anywhere from about ten degres to about thirty degrees with the vertical to achieve important advantages of the invention. In the disclosed embodiment the angle is eighteen degrees.

In some practical embodiments of the invention, reduction in face loading up to has been achieved.

FIGS. 7, 8 and 9 further diagrammaticaly illustrate additional theoretical considerations underlying the advantage of a forwardly inclined cutting wheel over one in which the face of the wheel is vertical. In FIG. 7 the wheel is vertical, as in FIG. 4. In FIG. 8 the wheel is slightly inclined forwardly, as in FIG. 5. In FIG. 9 the wheel has a still greater forward incline, as in FIG. 6.

Vertical axis line Z is tangent to stress curve in FIG. 7. Its distance from the base of the upright vertical wheel 10 is indicated by horizontal distance R. As the wheel is inclined forwardly, this distance increases, as indicated at S and T in FIGS. 8 and 9. This illustrates that the Weight of the soil ahead of the wheel is distributed over a larger base area, when the wheel is inclined, thus subjecting more of the soil to internal friction to sustain its weight. The face loading on the wheel is correspondingly reduced.

In FIGS. 8 and 9, axis line P represents a vertical plane through the base of the wheel. Cross hatched areas in FIG. 8 and 41 in FIG. 9 (the area is larger in FIG. 9) between axis line P and the inclined face 10 of the wheeel indicate the quantity of soil which is removed from pressure exerting relation to the wheel, as it is inclined forwardly from the vertical.

In addition to the foregoing, the inclined cutting wheel of the present invention makes possible improved steering control in the forward movement of the tunnel shield. The shield 11 typically has a hood 43 which projects forwardly of the shield and overhangs its bottom or floor 44. Accordingly, the front edge 45 of the shield has a forward incline.

If the shield has a cutting wheel rotating in a vertical plane, the hood 43 at the top of the shield would project farther forwardly from the face of the wheel than the shield would project from the face of the wheel near the floor 44. Accordingly, considerable earth material would have to extrude into the shield at its top before it is engaged by the cutting face of the wheel. By contrast, very little material is extruded into the shield at its bottom.

If the material is relatively hard, such as clay, the circumstances just mentioned result in greater back pressure at the top of the shield than at the bottom, with a pronounced tendency to deflect the shield upwardly from its intended course.

To the extent that the rotary wheel is inclined forwardly, the imbalance in back pressure caused by unequal extrusion is reduced. FIG. 1 illustrates a structure in which the wheel 10 is inclined at the same angle as the front edge 45 of the shield. Accordingly, assuming a uniform earth formation across the shield face, extrusion pressures are balanced at the top and bottom of the shield, and there will be no substantial tendency from extrusion pressures to deflect the wheel.

From the foregoing it is clear that steering control of the shield is improved by inclining the wheel forwardly toward a postion where it matches the incline of the front edge of the shield.

I claim:

1. A tunneling machine comprising a shield, a rotary cutting wheel confronting the major part of the tunnel face, and rotary support means for the wheel on which the plane in which the wheel rotates is inclined toward the angle of repose of the soil.

2. The machine of claim 1 in which said plane is disposed at an angle to the vertical in the range from ten degrees to thirty degrees.

3. In a tunneling machine having a shield, a rotary cutting wheel confronting the major part of the tunnel face and a support on which the wheel is rotatably mounted in the shield, the improvement for reducing the holding force required by the wheel and comprising means mounting said support in the shield at an angle to the vertical whereby the wheel rotates in a plane inclined toward the angle of repose of the soil.

4. The machine of claim 3 in which said means comprises an inclined bulkhead in the shield, an opening in the center of the bulkhead, complementary bearing races on the bulkhead and wheel about said opening and motor means to rotate the wheel on said bearing race.

5. The machine of claim 4 in which said motor means comprises a plurality of motors arranged in an arcuate series about the opening in said bulkhead and driving connections between said motors and said wheel.

6. The machine of claim 5 in which the bulkhead and wheel are inclined to the vertical in the range from ten degrees to thirty degrees.

7. The machine of claim 3 in which the shield has a front edge inclined forwardly from the vertical and toward which the wheel is also inclined.

8. A tunneling machine comprising a shield having a front edge inclined forwardly from the vertical, a rotary cutting wheel confronting the major part of the tunnel face, and rotary support means for the wheel on which the plane in which the wheel rotates is inclined toward the incline of the front edge of the shield.

5 6 9. The machine of claim 8 in which the incline of the FOREIGN PATENTS plane of the wheel is substantially the same as the incline 945 9 7 1956 of the front edge of the shield.' 1;1892

References Cited UNITED STATES PATENTS 5 ERNEST R. PURJ ER, Primary Examiner 3,309,142 3/1967 Winberg 299-43 3,355,215 11/1967 Haspert et a1. 299-31 X 37189;6185;29956, 90

340,759 4/1886 Brown 29956 X 3,350,889 11/1967 Sturm 299 33 x 10 

